In-vehicle positioning services refer to locating mobile devices within or relative to a vehicle. In-vehicle positioning may be used to provide personalized content to specific mobile devices and/or their locations within the vehicle. For example, a first mobile device may be providing a streaming video, while a second device is providing an online multi-player game. However, it is important to help prevent the operator of the vehicle from being distracted by mobile device content.
Techniques based on received signal strength indication (RSSI) from wireless communications, e.g., Wi-Fi and Bluetooth wireless access points, provide limited positional reliability. Complexities in vehicle environments cause radio waves to propagate in unpredictable ways, limiting the accuracy of positioning systems based on RSSI. Ultrasonic techniques (US), which transmit acoustic waves to microphones operate at lower frequencies than systems based on Wi-Fi and are susceptible to road noise interference.